1. Technical Field
The present invention relates to an electronic device, a method for producing the same, and an oscillator.
2. Related Art
Electronic devices in which a functional element such as a MEMS (Micro Electro Mechanical Systems) is disposed in a cavity formed on a substrate are known. For example, JP-A-2008-221435 describes an electronic device in which a functional element is formed on a substrate. The electronic device described in JP-A-2008-221435 is produced by forming a functional element on a substrate, forming an interlayer insulating layer so as to cover the functional element, and removing (release etching) the interlayer insulating layer located around the functional element to form a cavity.
With the recent progress in the micronization of electronic devices, the sizes of vias, contacts, guard rings and so forth are becoming very small. When a cavity as that of the electronic device described in JP-A-2008-221935 above is formed using a thin guard ring or the like, the side wall tends to collapse during release etching, so that the interlayer insulating layer may be removed in a region that is not supposed to be removed. This leads to a small margin in the time management for release etching. Also, there is a concern that the mechanical strength is insufficient because of the thin side wall.
When a transistor is additionally formed on the same substrate, it is necessary to interpose a titanium layer between the transistor and a contact in order to improve the junction therebetween. When a side wall that covers the cavity and the contact are formed in the same process, a titanium layer is formed on the side wall. Accordingly, the titanium layer is etched during release etching, so that the interlayer insulating layer may be removed in a region that is not supposed to be removed.